let obj = {
    name: '康少',
    age: 18,
    like: {
        a: '唱',
        b: '跳',
        c: 'rap',
    },
    a: undefined,
    b: null,
    e: {}
}
function shallowCopy(obj) {
    let newObj = {}
    for (let key in obj) {
        if (obj.hasOwnProperty(key)) { // 判断 key 是不是obj 显示拥有的
            newObj[key] = obj[key]
        }
    }
    return newObj
}